courtyard vs patio

courtyard

noun
  • An area, open to the sky, partially or wholly surrounded by walls or buildings. 

patio

noun
  • A paved outside area, adjoining a house, used for dining or recreation. 

  • An inner courtyard typical of traditional houses in some regions of Spain. 

How often have the words courtyard and patio occurred in a corpus of books? (source: Google Ngram Viewer )